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  <div class="SECT1">
    <h1 class="SECT1"><a name="CONFIGURATION" id="CONFIGURATION">3.
    Configuration</a></h1>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN369" id="AEN369">3.1. What exactly is an
      <span class="QUOTE">"actions"</span> file?</a></h3>

      <p><span class="APPLICATION">Privoxy</span> utilizes the concept of
      <span class="QUOTE">" <a href=
      "../user-manual/actions-file.html#ACTIONS" target=
      "_top">actions</a>"</span> that are used to manipulate and control web
      page data. <a href="../user-manual/actions-file.html" target=
      "_top">Actions files</a> are where these <a href=
      "../user-manual/actions-file.html#ACTIONS" target="_top">actions</a>
      that <span class="APPLICATION">Privoxy</span> could take while
      processing a certain request, are configured. Typically, you would
      define a set of default actions that apply globally to all URLs, then
      add exceptions to these defaults where needed. There is a wide array of
      actions available that give the user a high degree of control and
      flexibility on how to process each and every web page.</p>

      <p>Actions can be defined on a <a href=
      "../user-manual/actions-file.html#AF-PATTERNS" target="_top">URL
      pattern</a> basis, i.e. for single URLs, whole web sites, groups or
      parts thereof etc. Actions can also be grouped together and then
      applied to requests matching one or more patterns. There are many
      possible actions that might apply to any given site. As an example, if
      you are blocking <a href="http://en.wikipedia.org/wiki/Browser_cookie"
      target="_top">cookies</a> as one of your default actions, but need to
      accept cookies from a given site, you would need to define an exception
      for this site in one of your actions files, preferably in <tt class=
      "FILENAME">user.action</tt>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="ACTIONSS" id="ACTIONSS">3.2. The
      <span class="QUOTE">"actions"</span> concept confuses me. Please list
      some of these <span class="QUOTE">"actions"</span>.</a></h3>

      <p>For a comprehensive discussion of the actions concept, please refer
      to the <a href="../user-manual/actions-file.html" target="_top">actions
      file chapter</a> in the <a href="../user-manual/index.html" target=
      "_top">User Manual</a>. It includes a <a href=
      "../user-manual/actions-file.html#ACTIONS" target="_top">list of all
      actions</a> and an <a href=
      "../user-manual/actions-file.html#ACT-EXAMPLES" target="_top">actions
      file tutorial</a> to get you started.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN392" id="AEN392">3.3. How are actions
      files configured? What is the easiest way to do this?</a></h3>

      <p>Actions files are just text files in a special syntax and can be
      edited with a text editor. But probably the easiest way is to access
      <span class="APPLICATION">Privoxy</span>'s user interface with your web
      browser at <a href="http://config.privoxy.org/" target=
      "_top">http://config.privoxy.org/</a> (Shortcut: <a href="http://p.p/"
      target="_top">http://p.p/</a>) and then select <span class=
      "QUOTE">"<a href="http://config.privoxy.org/show-status" target=
      "_top">View &amp; change the current configuration</a>"</span> from the
      menu. Note that this feature must be explicitly enabled in the main
      config file (see <a href=
      "../user-manual/config.html#ENABLE-EDIT-ACTIONS" target=
      "_top">enable-edit-actions</a>).</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN401" id="AEN401">3.4. There are several
      different <span class="QUOTE">"actions"</span> files. What are the
      differences?</a></h3>

      <p>Please have a look at the <a href="../user-manual/actions-file.html"
      target="_top">the actions chapter</a> in the <a href=
      "../user-manual/index.html" target="_top">User Manual</a> for a
      detailed explanation.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="GETUPDATES" id="GETUPDATES">3.5. Where can I
      get updated Actions Files?</a></h3>

      <p>Based on your feedback and the continuing development, updates of
      <tt class="FILENAME">default.action</tt> will be made available from
      time to time on the <a href=
      "http://sourceforge.net/project/showfiles.php?group_id=11118" target=
      "_top">files section</a> of our <a href=
      "http://sf.net/projects/ijbswa/" target="_top">project page</a>.</p>

      <p>If you wish to receive an email notification whenever we release
      updates of <span class="APPLICATION">Privoxy</span> or the actions
      file, <a href=
      "http://lists.sourceforge.net/lists/listinfo/ijbswa-announce/" target=
      "_top">subscribe to our announce mailing list</a>,
      ijbswa-announce@lists.sourceforge.net.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="NEWCONFIG" id="NEWCONFIG">3.6. Can I use my
      old config files?</a></h3>

      <p>The syntax and purpose of configuration files has remained roughly
      the same throughout the 3.x series, but backwards compatibility is not
      guaranteed. Also each release contains updated, <span class=
      "QUOTE">"improved"</span> versions and it is therefore strongly
      recommended to install the newer configuration files and merge back
      your modifications.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="DIFFICULT" id="DIFFICULT">3.7. Why is the
      configuration so complicated?</a></h3>

      <p><span class="QUOTE">"Complicated"</span> is in the eye of the
      beholder. Those that are familiar with some of the underlying concepts,
      such as regular expression syntax, take to it like a fish takes to
      water. Also, software that tries hard to be <span class="QUOTE">"user
      friendly"</span>, often lacks sophistication and flexibility. There is
      always that trade-off there between power vs. easy-of-use. Furthermore,
      anyone is welcome to contribute ideas and implementations to enhance
      <span class="APPLICATION">Privoxy</span>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="YAHOO" id="YAHOO">3.8. How can I make my
      Yahoo/Hotmail/Gmail account work?</a></h3>

      <p>The default configuration shouldn't impact the usability of any of
      these services. It may, however, make all <a href=
      "http://en.wikipedia.org/wiki/Browser_cookie" target="_top">cookies</a>
      temporary, so that your browser will forget your login credentials in
      between browser sessions. If you would like not to have to log in
      manually each time you access those websites, simply turn off all
      cookie handling for them in the <tt class="FILENAME">user.action</tt>
      file. An example for yahoo might look like:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
# Allow all cookies for Yahoo login:
#
{ -<a href="../user-manual/actions-file.html#CRUNCH-INCOMING-COOKIES" target=
"_top">crunch-incoming-cookies</a> -<a href=
"../user-manual/actions-file.html#CRUNCH-OUTGOING-COOKIES" target=
"_top">crunch-outgoing-cookies</a> -<a href=
"../user-manual/actions-file.html#SESSION-COOKIES-ONLY" target=
"_top">session-cookies-only</a> }
.login.yahoo.com
</pre>
          </td>
        </tr>
      </table>

      <p>These kinds of sites are often quite complex and heavy with <a href=
      "http://en.wikipedia.org/wiki/Javascript" target="_top">Javascript</a>
      and thus <span class="QUOTE">"fragile"</span>. So if <span class=
      "emphasis EMPHASIS c3">still</span> a problem, we have an <a href=
      "../user-manual/actions-file.html#ALIASES" target="_top">alias</a> just
      for such sticky situations:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
# Gmail is a _fragile_ site:
#
{ <tt class="LITERAL">fragile</tt> }
 # Gmail is ...
 mail.google.com
</pre>
          </td>
        </tr>
      </table>

      <p>Be sure to flush your browser's caches whenever making these kinds
      of changes, just to make sure the changes <span class=
      "QUOTE">"take"</span>.</p>

      <p>Make sure the domain, host and path are appropriate as well. Your
      browser can tell you where you are specifically and you should use that
      information for your configuration settings. Note that above it is not
      referenced as <tt class="LITERAL">gmail.com</tt>, which is a valid
      domain name.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="CONFIGFILES" id="CONFIGFILES">3.9. What's
      the difference between the <span class="QUOTE">"Cautious"</span>,
      <span class="QUOTE">"Medium"</span> and <span class=
      "QUOTE">"Advanced"</span> defaults?</a></h3>

      <p>Configuring <span class="APPLICATION">Privoxy</span> is not entirely
      trivial. To help you get started, we provide you with three different
      default action <span class="QUOTE">"profiles"</span> in the web based
      actions file editor at <a href="http://config.privoxy.org/show-status"
      target="_top">http://config.privoxy.org/show-status</a>. See the
      <a class="CITETITLE c4" href="../user-manual/actions-file.html" target=
      "_top">User Manual</a> for a list of actions, and how the default
      profiles are set.</p>

      <p>Where the defaults are likely to break some sites, exceptions for
      known popular <span class="QUOTE">"problem"</span> sites are included,
      but in general, the more aggressive your default settings are, the more
      exceptions you will have to make later. New users are best to start off
      in <span class="QUOTE">"Cautious"</span> setting. This is safest and
      will have the fewest problems. See the <a class="CITETITLE c4" href=
      "../user-manual/index.html" target="_top">User Manual</a> for a more
      detailed discussion.</p>

      <p>It should be noted that the <span class="QUOTE">"Advanced"</span>
      profile (formerly known as the <span class=
      "QUOTE">"Adventuresome"</span> profile) is more aggressive, and will
      make use of some of <span class="APPLICATION">Privoxy's</span> advanced
      features. Use at your own risk!</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="BROWSECONFIG" id="BROWSECONFIG">3.10. Why
      can I change the configuration with a browser? Does that not raise
      security issues?</a></h3>

      <p>It may seem strange that regular users can edit the config files
      with their browsers, although the whole <tt class=
      "FILENAME">/etc/privoxy</tt> hierarchy belongs to the user <span class=
      "QUOTE">"privoxy"</span>, with only 644 permissions.</p>

      <p>When you use the browser-based editor, <span class=
      "APPLICATION">Privoxy</span> itself is writing to the config files.
      Because <span class="APPLICATION">Privoxy</span> is running as the user
      <span class="QUOTE">"privoxy"</span>, it can update its own config
      files.</p>

      <p>If you run <span class="APPLICATION">Privoxy</span> for multiple
      untrusted users (e.g. in a LAN) or aren't entirely in control of your
      own browser, you will probably want to make sure that the web-based
      editor and remote toggle features are <span class="QUOTE">"off"</span>
      by setting <span class="QUOTE">"<tt class="LITERAL"><a href=
      "../user-manual/config.html#ENABLE-EDIT-ACTIONS" target=
      "_top">enable-edit-actions</a> 0</tt>"</span> and <span class=
      "QUOTE">"<tt class="LITERAL"><a href=
      "../user-manual/config.html#ENABLE-REMOTE-TOGGLE" target=
      "_top">enable-remote-toggle</a> 0</tt>"</span> in the <a href=
      "../user-manual/config.html" target="_top">main configuration
      file</a>.</p>

      <p>As of <span class="APPLICATION">Privoxy</span> 3.0.7 these options
      are disabled by default.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN489" id="AEN489">3.11. What is the
      <tt class="FILENAME">default.filter</tt> file? What is a <span class=
      "QUOTE">"filter"</span>?</a></h3>

      <p>The <a href="../user-manual/filter-file.html" target=
      "_top"><tt class="FILENAME">default.filter</tt></a> file is where
      <span class="emphasis EMPHASIS c3">filters</span> as supplied by the
      developers are defined. Filters are a special subset of actions that
      can be used to modify or remove web page content or headers on the fly.
      Content filters can be applied to <span class=
      "emphasis EMPHASIS c3">anything</span> in the page source, header
      filters can be applied to either server or client headers. Regular
      expressions are used to accomplish this.</p>

      <p>There are a number of pre-defined filters to deal with common
      annoyances. The filters are only defined here, to invoke them, you need
      to use the <a href="../user-manual/actions-file.html#FILTER" target=
      "_top"><tt class="LITERAL">filter</tt> action</a> in one of the actions
      files. Content filtering is automatically disabled for inappropriate
      MIME types, but if you know better than Privoxy what should or should
      not be filtered you can filter any content you like.</p>

      <p>Filters should <span class="emphasis EMPHASIS c3">not</span> be
      confused with <a href="../user-manual/actions-file.html#BLOCK" target=
      "_top"><tt class="LITERAL">blocks</tt></a>, which is a completely
      different action, and is more typically used to block ads and unwanted
      sites.</p>

      <p>If you are familiar with regular expressions, and HTML, you can look
      at the provided <tt class="FILENAME">default.filter</tt> with a text
      editor and define your own filters. This is potentially a very powerful
      feature, but requires some expertise in both regular expressions and
      HTML/HTTP. You should place any modifications to the default filters,
      or any new ones you create in a separate file, such as <tt class=
      "FILENAME">user.filter</tt>, so they won't be overwritten during
      upgrades. The ability to define multiple filter files in <tt class=
      "FILENAME">config</tt> is a new feature as of v. 3.0.5.</p>

      <p>There is no GUI editor option for this part of the configuration,
      but you can disable/enable the various pre-defined filters of the
      included <tt class="FILENAME">default.filter</tt> file with the
      <a href="http://config.privoxy.org/show-status" target="_top">web-based
      actions file editor</a>. Note that the custom actions editor must be
      explicitly enabled in the main config file (see <a href=
      "../user-manual/config.html#ENABLE-EDIT-ACTIONS" target=
      "_top">enable-edit-actions</a>).</p>

      <p>If you intend to develop your own filters, you might want to have a
      look at <a href="http://www.fabiankeil.de/sourcecode/pft/" target=
      "_top">Privoxy-Filter-Test</a>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="LANCONFIG" id="LANCONFIG">3.12. How can I
      set up Privoxy to act as a proxy for my LAN?</a></h3>

      <p>By default, <span class="APPLICATION">Privoxy</span> only responds
      to requests from <tt class="LITERAL">127.0.0.1</tt> (localhost). To
      have it act as a server for a network, this needs to be changed in the
      <a href="../user-manual/config.html" target="_top">main configuration
      file</a>. Look for the <tt class="LITERAL"><a href=
      "../user-manual/config.html#LISTEN-ADDRESS" target=
      "_top">listen-address</a></tt> option, which may be commented out with
      a <span class="QUOTE">"#"</span> symbol. Make sure it is uncommented,
      and assign it the address of the LAN gateway interface, and port number
      to use. Assuming your LAN address is 192.168.1.1 and you wish to run
      <span class="APPLICATION">Privoxy</span> on port 8118, this line should
      look like:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
  listen-address  192.168.1.1:8118
</pre>
          </td>
        </tr>
      </table>

      <p>Save the file, and restart <span class="APPLICATION">Privoxy</span>.
      Configure all browsers on the network then to use this address and port
      number.</p>

      <p>Alternately, you can have <span class="APPLICATION">Privoxy</span>
      listen on all available interfaces:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
  listen-address    :8118
</pre>
          </td>
        </tr>
      </table>

      <p>And then use <span class="APPLICATION">Privoxy's</span> <a href=
      "../user-manual/config.html#PERMIT-ACCESS" target=
      "_top">permit-access</a> feature to limit connections. A firewall in
      this situation is recommended as well.</p>

      <p>The above steps should be the same for any TCP network, regardless
      of operating system.</p>

      <p>If you run <span class="APPLICATION">Privoxy</span> on a LAN with
      untrusted users, we recommend that you double-check the <a href=
      "../user-manual/config.html#ACCESS-CONTROL" target="_top">access
      control and security</a> options!</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN540" id="AEN540">3.13. Instead of ads,
      now I get a checkerboard pattern. I don't want to see
      anything.</a></h3>

      <p>The replacement for blocked images can be controlled with the
      <a href="../user-manual/actions-file.html#SET-IMAGE-BLOCKER" target=
      "_top"><tt class="LITERAL">set-image-blocker</tt> action</a>. You have
      the choice of a checkerboard pattern, a transparent 1x1 GIF image (aka
      <span class="QUOTE">"blank"</span>), or a redirect to a custom image of
      your choice. Note that this choice only has effect for images which are
      blocked as images, i.e. whose URLs match both a <tt class=
      "LITERAL"><a href="../user-manual/actions-file.html#HANDLE-AS-IMAGE"
      target="_top">handle-as-image</a></tt> <span class=
      "emphasis EMPHASIS c3">and</span> <tt class="LITERAL"><a href=
      "../user-manual/actions-file.html#BLOCK" target="_top">block</a></tt>
      action.</p>

      <p>If you want to see nothing, then change the <a href=
      "../user-manual/actions-file.html#SET-IMAGE-BLOCKER" target=
      "_top"><tt class="LITERAL">set-image-blocker</tt> action</a> to
      <span class="QUOTE">"blank"</span>. This can be done by editing the
      <tt class="FILENAME">user.action</tt> file, or through the <a href=
      "http://config.privoxy.org/show-status" target="_top">web-based actions
      file editor</a>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN557" id="AEN557">3.14. Why would anybody
      want to see a checkerboard pattern?</a></h3>

      <p>Remember that <a href="general.html#WHATSANAD">telling which image
      is an ad and which isn't</a>, is an educated guess. While we hope that
      the standard configuration is rather smart, it will make occasional
      mistakes. The checkerboard image is visually decent, and it shows you
      where images have been blocked, which can be very helpful in case some
      navigation aid or otherwise innocent image was erroneously blocked. It
      is recommended for new users so they can <span class=
      "QUOTE">"see"</span> what is happening. Some people might also enjoy
      seeing how many banners they <span class=
      "emphasis EMPHASIS c3">don't</span> have to see.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="AEN563" id="AEN563">3.15. I see some images
      being replaced with text instead of the checkerboard image. Why and how
      do I get rid of this?</a></h3>

      <p>This happens when the banners are not embedded in the HTML code of
      the page itself, but in separate HTML (sub)documents that are loaded
      into (i)frames or (i)layers, and these external HTML documents are
      blocked. Being non-images they get replaced by a substitute HTML page
      rather than a substitute image, which wouldn't work out technically,
      since the browser expects and accepts only HTML when it has requested
      an HTML document.</p>

      <p>The substitute page adapts to the available space and shows itself
      as a miniature two-liner if loaded into small frames, or full-blown
      with a large red "BLOCKED" banner if space allows.</p>

      <p>If you prefer the banners to be blocked by images, you must see to
      it that the HTML documents in which they are embedded are not blocked.
      Clicking the <span class="QUOTE">"See why"</span> link offered in the
      substitute page will show you which rule blocked the page. After
      changing the rule and un-blocking the HTML documents, the browser will
      try to load the actual banner images and the usual image blocking will
      (hopefully!) kick in.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="SRVANY" id="SRVANY">3.16. Can Privoxy run as
      a service on Win2K/NT/XP?</a></h3>

      <p>Yes. Version 3.0.5 introduces full <span class=
      "APPLICATION">Windows</span> service functionality. See <a href=
      "../user-manual/installation.html#installation-pack-win" target=
      "_top">the <i class="CITETITLE">User Manual</i></a> for details on how
      to install and configure <span class="APPLICATION">Privoxy</span> as a
      service.</p>

      <p>Earlier 3.x versions could run as a system service using <b class=
      "COMMAND">srvany.exe</b>. See the discussion at <a href=
      "http://sourceforge.net/tracker/?func=detail&amp;atid=361118&amp;aid=485617&amp;group_id=11118"
      target=
      "_top">http://sourceforge.net/tracker/?func=detail&amp;atid=361118&amp;aid=485617&amp;group_id=11118</a>,
      for details, and a sample configuration.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="OTHERPROXY" id="OTHERPROXY">3.17. How can I
      make Privoxy work with other proxies?</a></h3>

      <p>This can be done and is often useful to combine the benefits of
      <span class="APPLICATION">Privoxy</span> with those of a another proxy,
      for example to cache content. See the <a href=
      "../user-manual/config.html#FORWARDING" target="_top">forwarding
      chapter</a> in the <a href="../user-manual/index.html" target=
      "_top">User Manual</a> which describes how to do this. If you intend to
      use Privoxy with Tor, please also have a look at <a href=
      "misc.html#TOR">How do I use Privoxy together with Tor</a>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="PORT-80" id="PORT-80">3.18. Can I just set
      Privoxy to use port 80 and thus avoid individual browser
      configuration?</a></h3>

      <p>No, its more complicated than that. This only works with special
      kinds of proxies known as <span class="QUOTE">"intercepting"</span>
      proxies (<a href="configuration.html#INTERCEPTING">see below</a>).</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="TRANSPARENT" id="TRANSPARENT">3.19. Can
      Privoxy run as a <span class="QUOTE">"transparent"</span>
      proxy?</a></h3>

      <p>The whole idea of Privoxy is to modify client requests and server
      responses in all sorts of ways and therefore it's not a transparent
      proxy as described in <a href="http://tools.ietf.org/html/rfc2616"
      target="_top">RFC 2616</a>.</p>

      <p>However, some people say <span class="QUOTE">"transparent
      proxy"</span> when they mean <span class="QUOTE">"intercepting
      proxy"</span>. If you are one of them, please read the <a href=
      "configuration.html#INTERCEPTING">next entry</a>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="INTERCEPTING" id="INTERCEPTING">3.20. Can
      Privoxy run as a <span class="QUOTE">"intercepting"</span>
      proxy?</a></h3>

      <p><span class="APPLICATION">Privoxy</span> can't intercept traffic
      itself, but it can handle requests that where intercepted and
      redirected with a packet filter (like <span class=
      "APPLICATION">PF</span> or <span class="APPLICATION">iptables</span>),
      as long as the <tt class="LITERAL">Host</tt> header is present.</p>

      <p>As the <tt class="LITERAL">Host</tt> header is required by HTTP/1.1
      and as most web sites rely on it anyway, this limitation shouldn't be a
      problem.</p>

      <p>Please refer to your packet filter's documentation to learn how to
      intercept and redirect traffic into <span class=
      "APPLICATION">Privoxy</span>. Afterward you just have to configure
      <span class="APPLICATION">Privoxy</span> to <a href=
      "../user-manual/config.html#ACCEPT-INTERCEPTED-REQUESTS" target=
      "_top">accept intercepted requests</a>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="OUTLOOK" id="OUTLOOK">3.21. How can I
      configure Privoxy for use with Outlook?</a></h3>

      <p>Versions of <span class="APPLICATION">Outlook</span> prior to Office
      2007, use <span class="APPLICATION">Internet Explorer</span> components
      to both render HTML, and fetch any HTTP requests that may be embedded
      in an HTML email. So however you have <span class=
      "APPLICATION">Privoxy</span> configured to work with IE, this
      configuration should automatically be shared, at least with older
      version of Internet Explorer.</p>

      <p>Starting with Office 2007, Microsoft is instead using the MS-Word
      rendering engine with Outlook. It is unknown whether this can be
      configured to use a proxy.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="OUTLOOK-MORE" id="OUTLOOK-MORE">3.22. How
      can I have separate rules just for HTML mail?</a></h3>

      <p>The short answer is, you can't. <span class=
      "APPLICATION">Privoxy</span> has no way of knowing which particular
      application makes a request, so there is no way to distinguish between
      web pages and HTML mail. <span class="APPLICATION">Privoxy</span> just
      blindly proxies all requests. In the case of <span class=
      "APPLICATION">Outlook Express</span> (see above), OE uses IE anyway,
      and there is no way for <span class="APPLICATION">Privoxy</span> to
      ever be able to distinguish between them (nor could any other proxy
      type application for that matter).</p>

      <p>For a good discussion of some of the issues involved (including
      privacy and security issues), see <a href=
      "http://sourceforge.net/tracker/?func=detail&amp;atid=211118&amp;aid=629518&amp;group_id=11118"
      target=
      "_top">http://sourceforge.net/tracker/?func=detail&amp;atid=211118&amp;aid=629518&amp;group_id=11118</a>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="SNEAKY-COOKIES" id="SNEAKY-COOKIES">3.23. I
      sometimes notice cookies sneaking through. How?</a></h3>

      <p><a href="http://en.wikipedia.org/wiki/Browser_cookie" target=
      "_top">Cookies</a> can be set in several ways. The classic method is
      via the <tt class="LITERAL">Set-Cookie</tt> HTTP header. This is
      straightforward, and an easy one to manipulate, such as the
      <span class="APPLICATION">Privoxy</span> concept of <a href=
      "../user-manual/actions-file.html#SESSION-COOKIES-ONLY" target=
      "_top">session-cookies-only</a>. There is also the possibility of using
      <a href="http://en.wikipedia.org/wiki/Javascript" target=
      "_top">Javascript</a> to set cookies (<span class=
      "APPLICATION">Privoxy</span> calls these <tt class=
      "LITERAL">content-cookies</tt>). This is trickier because the syntax
      can vary widely, and thus requires a certain amount of guesswork. It is
      not realistic to catch all of these short of disabling Javascript,
      which would break many sites. And lastly, if the cookies are embedded
      in a HTTPS/SSL secure session via Javascript, they are beyond
      <span class="APPLICATION">Privoxy's</span> reach.</p>

      <p>All in all, <span class="APPLICATION">Privoxy</span> can help manage
      cookies in general, can help minimize the loss of privacy posed by
      cookies, but can't realistically stop all cookies.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="EVIL-COOKIES" id="EVIL-COOKIES">3.24. Are
      all cookies bad? Why?</a></h3>

      <p>No, in fact there are many beneficial uses of <a href=
      "http://en.wikipedia.org/wiki/Browser_cookie" target=
      "_top">cookies</a>. Cookies are just a method that browsers can use to
      store data between pages, or between browser sessions. Sometimes there
      is a good reason for this, and the user's life is a bit easier as a
      result. But there is a long history of some websites taking advantage
      of this layer of trust, and using the data they glean from you and your
      browsing habits for their own purposes, and maybe to your potential
      detriment. Such sites are using you and storing their data on your
      system. That is why the privacy conscious watch from whom those cookies
      come, and why they really <span class=
      "emphasis EMPHASIS c3">need</span> to be there.</p>

      <p>See the <a href="http://en.wikipedia.org/wiki/Browser_cookie"
      target="_top">Wikipedia cookie definition</a> for more.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="ALLOW-COOKIES" id="ALLOW-COOKIES">3.25. How
      can I allow permanent cookies for my trusted sites?</a></h3>

      <p>There are several actions that relate to cookies. The default
      behavior is to allow only <span class="QUOTE">"session cookies"</span>,
      which means the cookies only last for the current browser session. This
      eliminates most kinds of abuse related to cookies. But there may be
      cases where you want cookies to last.</p>

      <p>To disable all cookie actions, so that cookies are allowed
      unrestricted, both in and out, for <tt class=
      "LITERAL">example.com</tt>:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
 { -crunch-incoming-cookies -crunch-outgoing-cookies -session-cookies-only -filter{content-cookies} }
  .example.com
</pre>
          </td>
        </tr>
      </table>

      <p>Place the above in <tt class="FILENAME">user.action</tt>. Note that
      some of these may be off by default anyway, so this might be redundant,
      but there is no harm being explicit in what you want to happen.
      <tt class="FILENAME">user.action</tt> includes an alias for this
      situation, called <tt class="LITERAL">allow-all-cookies</tt>.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="MULTIPLES" id="MULTIPLES">3.26. Can I have
      separate configurations for different users?</a></h3>

      <p>Each instance of <span class="APPLICATION">Privoxy</span> has its
      own configuration, including such attributes as the TCP port that it
      listens on. What you can do is run multiple instances of <span class=
      "APPLICATION">Privoxy</span>, each with a unique <a href=
      "../user-manual/config.html#LISTEN-ADDRESS" target=
      "_top">listen-address</a> configuration setting, and configuration
      path, and then each of these can have their own configurations. Think
      of it as per-port configuration.</p>

      <p>Simple enough for a few users, but for large installations, consider
      having groups of users that might share like configurations.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="WHITELISTS" id="WHITELISTS">3.27. Can I
      set-up Privoxy as a whitelist of <span class="QUOTE">"good"</span>
      sites?</a></h3>

      <p>Sure. There are a couple of things you can do for simple
      white-listing. Here's one real easy one:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
 ############################################################
 # Blacklist
 ############################################################
 { <a href="../user-manual/actions-file.html#BLOCK" target=
"_top">+block</a> }
 / # Block *all* URLs

 ############################################################
 # Whitelist
 ############################################################
 { <a href="../user-manual/actions-file.html#BLOCK" target=
"_top">-block</a> }
  kids.example.com
  toys.example.com
  games.example.com
</pre>
          </td>
        </tr>
      </table>

      <p>This allows access to only those three sites by first blocking all
      URLs, and then subsequently allowing three specific exceptions.</p>

      <p>Another approach is <span class="APPLICATION">Privoxy's</span>
      <tt class="LITERAL">trustfile</tt> concept, which incorporates the
      notion of <span class="QUOTE">"trusted referrers"</span>. See the
      <a href="../user-manual/config.html#TRUSTFILE" target="_top">Trust
      documentation</a> for details.</p>

      <p>These are fairly simple approaches and are not completely foolproof.
      There are various other configuration options that should be disabled
      (described elsewhere here and in <a href="../user-manual/" target=
      "_top">the User Manual</a>) so that users can't modify their own
      configuration and easily circumvent the whitelist.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="NO-ADBLOCK" id="NO-ADBLOCK">3.28. How can I
      turn off ad-blocking?</a></h3>

      <p>Ad blocking is achieved through a complex application of various
      <span class="APPLICATION">Privoxy</span> <a href=
      "../user-manual/actions-file.html" target="_top">actions</a>. These
      actions are deployed against simple images, banners, flash animations,
      text pages, JavaScript, pop-ups and pop-unders, etc., so its not as
      simple as just turning one or two actions off. The various actions that
      make up <span class="APPLICATION">Privoxy</span> ad blocking are
      hard-coded into the default configuration files. It has been assumed
      that everyone using <span class="APPLICATION">Privoxy</span> is
      interested in this particular feature.</p>

      <p>If you want to do without this, there are several approaches you can
      take: You can manually undo the many block rules in <tt class=
      "FILENAME">default.action</tt>. Or even easier, just create your own
      <tt class="FILENAME">default.action</tt> file from scratch without the
      many ad blocking rules, and corresponding exceptions. Or lastly, if you
      are not concerned about the additional blocks that are done for privacy
      reasons, you can very easily over-ride <span class=
      "emphasis EMPHASIS c3">all</span> blocking with the following very
      simple rule in your <tt class="FILENAME">user.action</tt>:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
 # Unblock everybody, everywhere
 { <a href="../user-manual/actions-file.html#BLOCK" target=
"_top">-block</a> }
 / # UN-Block *all* URLs
</pre>
          </td>
        </tr>
      </table>

      <p>Or even a more comprehensive reversing of various ad related
      actions:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
 # Unblock everybody, everywhere, and turn off appropriate filtering, etc
 { <a href="../user-manual/actions-file.html#BLOCK" target=
"_top">-block</a> \
  <a href="../user-manual/actions-file.html#FILTER-BANNERS-BY-SIZE" target=
"_top">-filter{banners-by-size}</a> \
  <a href="../user-manual/actions-file.html#FILTER-BANNERS-BY-LINK" target=
"_top">-filter{banners-by-link}</a> \
  <tt class="LITERAL">allow-popups</tt> \
 }
 / # UN-Block *all* URLs and allow ads
</pre>
          </td>
        </tr>
      </table>

      <p>This last <span class="QUOTE">"action"</span> in this compound
      statement, <tt class="LITERAL">allow-popups</tt>, is an <a href=
      "../user-manual/actions-file.html#ALIASES" target="_top">alias</a> that
      disables various pop-up blocking features.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="TEMPLATES" id="TEMPLATES">3.29. How can I
      have custom template pages, like the <span class=
      "emphasis EMPHASIS c3">BLOCKED</span> page?</a></h3>

      <p><span class="APPLICATION">Privoxy</span> <span class=
      "QUOTE">"templates"</span> are specialized text files utilized by
      <span class="APPLICATION">Privoxy</span> for various purposes and can
      easily be modified using any text editor. All the template pages are
      installed in a sub-directory appropriately named: <tt class=
      "FILENAME">templates</tt>. Knowing something about HTML syntax will of
      course be helpful.</p>

      <p>Be forewarned that the default templates are subject to being
      overwritten during upgrades. You can, however, create completely new
      templates, place them in another directory and specify the alternate
      path in the main <tt class="FILENAME">config</tt>. For details, have a
      look at the <a href="../user-manual/config.html#templdir" target=
      "_top">templdir</a> option.</p>
    </div>

    <div class="SECT2">
      <h3 class="SECT2"><a name="BLOCKALL" id="BLOCKALL">3.30. How can I
      remove the <span class="QUOTE">"Go There Anyway"</span> link from the
      <span class="emphasis EMPHASIS c3">BLOCKED</span> page?</a></h3>

      <p>There is more than one way to do it (although Perl is not
      involved).</p>

      <p>Editing the BLOCKED template page (see above) may dissuade some
      users, but this method is easily circumvented. Where you need this
      level of control, you might want to build <span class=
      "APPLICATION">Privoxy</span> from source, and disable various features
      that are available as compile-time options. You should <b class=
      "COMMAND">configure</b> the sources as follows:</p>

      <table class="c2" border="0" width="100%">
        <tr>
          <td>
            <pre class="SCREEN">
 ./configure  --disable-toggle  --disable-editor  --disable-force
</pre>
          </td>
        </tr>
      </table>

      <p>This will create an executable with hard-coded security features so
      that <span class="APPLICATION">Privoxy</span> does not allow easy
      bypassing of blocked sites, or changing the current configuration via
      any connected user's web browser.</p>

      <p>Finally, all of these features can also be toggled on/off via
      options in <span class="APPLICATION">Privoxy's</span> main <a href=
      "../user-manual/config.html#ACCESS-CONTROL" target="_top">config</a>
      file which means you don't have to recompile anything.</p>
    </div>
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